Lung cancer is a huge public health problem, both in terms of morbidity and mortality. No effective prevention or reduction strategy has been found despite a wealth of investigation. Non-steroidal anti- inflammatory drugs (NSAIDs) have been associated with a decreased risk of incident lung cancer. However, this association has not been confirmed and many previous trials have had important limitations. Furthermore, the effects of NSAIDs in relation to their specific COX-2 inhibition, the mechanism felt to be crucial for lung cancer pathogenensis, has not been explored. This project will attempt to answer the former question more rigorously and investigate the specific role of COX-2 blockade in lung cancer risk. We propose to use a large, population-based, cohort to examine the relationship between NSAID use and lung cancer incidence. Cox proportional hazards analysis will be performed on the exposure variables of interest, namely categories of NSAID use based on duration and intensity, after controlling for multiple confounders. Subgroup analyses will be performed according to the type of lung cancer as well as the differential selectivity of NSAIDs on the COX-2 enzyme. The results of this study will provide extremely useful information regarding possible chemopreventative effects of NSAIDs as well as elucidate possible underlying biologic pathways in lung cancer pathogenesis. [unreadable] [unreadable] [unreadable] [unreadable]